Post-exposure prophylaxis (PEP) may stop you developing an HIV infection if you’ve been exposed to the virus. However, it doesn’t always work.

Post-exposure prophylaxis (PEP) may stop you developing an HIV infection if you’ve been exposed to the virus. However, it doesn’t always work.

You may have been exposed to HIV if you've:

had unprotected sex (without using a condom)

had sex with someone with HIV and the condom broke

been injured with an HIV-infected needle

What is PEP?

PEP is a course of anti-HIV medication. You must start the treatment as soon as possible after you’ve been exposed to HIV, ideally within a few hours. The medicines must be taken every day for four weeks.

PEP is unlikely to work if it’s started after 72 hours (three days) and it won’t usually be prescribed after this time.

PEP makes infection with HIV less likely. However, it’s not a cure for HIV and it doesn’t work in all cases. Some strains of HIV aren't affected by the medicines.